a lic. oec. (licentiatus oeconomiaeis) is equivalent to a Masters in Economics, and HSG means that the degree is awarded from University of St. Gallen in Switzerland. so you could translate it as something like「経済学修士（ザンクトガレン大学）」.

I might just add that you would have to bear in mind that degree system in higher education differ greatly from one country to another and that (although I said above that a licentiatus (which is a degree in German/Swiss higher education system) is equivalent to a Masters (in the UK - sorry but I am not familiar with the American university system so I cannot generalise any further), there is never a total 'equivalence' if you know what I mean. also, I have seen examples where lic. oec. is translated as MBA, but I know that usually lic. oec. is more general than MBA.

hope this helps.